Automatic GCR software

[Louis Dery]

Hi Gordo,
I’m interested about your sample images. Is it possible to send me your original RGB. I would like to compare GCR you’ve made with it.

Thanks!
Louis

 

[Louis Dery]

Hi Louis, I don't think a press knows about algorithms
I think the problem stems from the poor quality of the black ink that is often used in newspaper work. Because the GCR separation has a much larger component of black ink - any issues will therefore be magnified.

best, gordo (not affiliated with Kodak)

I agree that a press don’t knows about algorithms. What I ment was about the way Black is "calculated" to fit with the remaining CMY. This makes a big difference how much any issue with Black is magnified like you said.

best, Louis

 

[gordo]

Hi Gordo,
I’m interested about your sample images. Is it possible to send me your original RGB. I would like to compare GCR you’ve made with it.
Thanks!
Louis

Sure, just remember that I did crank up the separation to demonstrate the differences.
You can download the original image from here:
YouSendIt - Send large files - transfer delivery - FTP Replacement
best, gordo

 

[Lukas Engqvist]

There was a swedish study/scientific research made showing that UCR is just a special case of GCR. As far as vibracy isn't part of the issue of limiting ink to be able to keep densities at higher normal values and maintain printability (wich also generates a wider gamut).
As far as the discussion about yellow (printed first in Newspapers) part of the equation is that inks contain much of what is not pigment so the first colour, as stated in one of the posts will have the same effect as varnish in building up a saturation in the substrate with all those things that are not pigment.
I would toss in the whole issue of digital printing wich has different pigments…Â*there too there can be a problem with too much ink…Â*but even if the problem is different the techniques for limiting ink are still applicable.
It is very interesting to follow these discussions and having forums such as this is enriching letting many minds ponder on the differences and similarities in differing printing environments.

 

[otherthoughts]

I should state from the outset that the vast bulk of my experience involves sheet-fed offset commercial printing on coated stock. Web-offset on newsprint, is not my strongest suit. I felt that a disclaimer was needed before giving my opinion, just to avoid any confusion.

Firstly I would like to point out that there is a third type of separation possible. Separations having neither UCR or GCR. In fact that was the original type of separation. UCR and GCR are just branches on the separation tree.

What does UCR do for us?

• Lends stability to our neutrals. The Black ink is inherently neutral.
• This stability is most helpful in those areas of our color management that are the least stable, namely, the pressroom.
• Decreasing the TAC value typically shortens drying times (sheet-fed).
• Allows the pressman to apply less spray powder between sheets, this makes printing the reverse side easier and quicker (sheet-fed).
• Can reduce curling at the tail end of the sheet on heavy coverage jobs (sheet-fed).
• The black ink is cheaper than the CMY inks.
• If black is your first down ink, it may expose hidden defects in the press’s state of being (not good).
• Will reduce the overall gloss of the sheet, often a bad thing for high end presswork.
• Uncoated stocks often “dry-back” more than coated stocks, uncoated stocks printed with UCR often have an even lower tonal range than they would have otherwise.

What does GCR do for us?

• Take all of the items I listed for UCR and expand them outwards so that they also affect most colors.
• The stability you may have gained in the neutrals is often undone by instabilities introduced in your color.
• GCR saves even more money on ink than UCR.
• In high quality printing, labor and paper represent the greatest cost items. I would guess that ink only represents about 8% of the total cost. Any setbacks in make-ready times easily offset the savings on inks for short run jobs.
• With web-offset printing on newsprint and very long runs, I would guess that the cost of ink would be of greater significance.
• Black is the highest contrast ink. The greatest detail capabilities exist near the mid-tones and taper off from there. If the GCR is done correctly and the black printing plate begins to look like a B/W halftone. It is possible to attain much better shape and detail on newsprint and web-offset printing (not for your average Joes). This may outweigh the sacrifice in overall gloss and lower total overprint density.

Well that’s my input for what it’s worth. UCR and GCR are great tools when applied correctly and appropriately.

I also have a question for those that are familiar with re-separation software. How well are the un-sharp masking details migrated from the CMY separations to the Black separation when aiming at heavy GCR re-separations?

 

[meddington]

I also have a question for those that are familiar with re-separation software. How well are the un-sharp masking details migrated from the CMY separations to the Black separation when aiming at heavy GCR re-separations?

Interesting question, though I haven't noticed any loss of detail in the slightest. I'm using ProfileMaker and Profiler to generate GCR profiles rather than the specific ink saving software (GMG Alwan Perfx Oris), but I wouldn't expect this to be an issue.

 

[Louis Dery]

Interesting question, though I haven't noticed any loss of detail in the slightest. I'm using ProfileMaker and Profiler to generate GCR profiles rather than the specific ink saving software (GMG Alwan Perfx Oris), but I wouldn't expect this to be an issue.

Hi Mike,
Same results for me. No differences.

About GCR profiles made with ProfileMaker and Profiler, have you been able to do good profiles with strong (Max) GCR with TAC lower than 250% without loss of shadow saturation (ex. wine reds, etc.)?

Louis

 

[meddington]

HiAbout GCR profiles made with ProfileMaker and Profiler, have you been able to do good profiles with strong (Max) GCR with TAC lower than 250% without loss of shadow saturation (ex. wine reds, etc.)?

Lower than 250% doesn't come up here much, as we're a commercial sheetfed shop, but I will say that there is a tendency to have deep reds loose a bit of saturation. I don't consider this a significant loss, only a few percent, but its something I've noticed on the separation side when softproofing. Can't say that I've noticed it in the end product at all.

 

[Louis Dery]

Interesting question, though I haven't noticed any loss of detail in the slightest. I'm using ProfileMaker and Profiler to generate GCR profiles rather than the specific ink saving software (GMG Alwan Perfx Oris), but I wouldn't expect this to be an issue.

Hi Mike,

About your GCR profiles… were do commonly you use (apply) them in your workflow?
Photoshop only or elsewhere for complete page contents?

Just curious.

Louis

 

[meddington]

About your GCR profiles… were do commonly you use (apply) them in your workflow?
Photoshop only or elsewhere for complete page contents?
s

Primarily Photoshop as we're most often at the beginning of the workflow. We have also implemented DVLs through Dalim Twist as well though.